The proposed studies will provide basic information and improve our understanding regarding the control and cellular origin of collagenase and gelatinase activity during follicular development and ovulation as well as during the life span of the corpus luteum. The goal of this proposal is to investigate the changes and regulation of the ovarian metalloproteinases collagenase and gelatinase and an associated inhibitor during the reproductive cycle of the rat. Using biochemical, immunohistochemical, and in vitro techniques, the present experiments are designed to determine: 1) if the activities of collagenase, gelatinase and the inhibitor change during cycles of ovarian connective tissue remodeling; 2) if enzyme and inhibitor activities are hormonally regulated and what specific hormones stimulate activity; 3) the physiochemical characteristics of the inhibitor and whether it is serum or tissue-derived; and 4) the cellular location and quantitative changes in collagenase during the follicular and luteal periods. The first aspect of this study will use biochemical analyses to examine the Changes in the activities of collagenase, gelatinase, and a metalloproteinase inhibitor in ovaries collected during follicular and luteal development in vivo. Second, the role of gonadotropins, cyclic nucleotides, prostaglandins, and steroids in regulating collagenase, gelatinase, and inhibitor activity will be studied in vitro with a granulosa and luteal cell culture model and in vivo following intrabursal administration. Third, the inhibitor's physiochemical properties will be characterized. We will expand our exciting preliminary observations which confirm the existence of an inhibitor and determine whether the inhibitor has the characteristics of tissue inhibitors of metalloproteinases observed in other tissues. The final goal of this investigation will be to elucidate the cellular origin and changes in collagenase localization during follicular development and rupture and during luteal formation and regression by immunohistochemistry. The information derived from the proposed studies will provide insight into the basic mechanisms of ovarian connective tissue remodeling and may ultimately lead to better methods for promoting or inhibiting follicular rupture and luteal function. Although these studies are limited to the rat, the findings may in the future be applicable to the human and relevant to abnormalities such as luteinized unruptured follicles where the steroidal environment is altered and proteolytic breakdown does not occur. Furthermore, the information from the proposed research may be of significance beyond reproductive physiology since metalloproteinases have been implicated in a number of pathological processes such as arthritis and tumor growth.